Keratoconus is a bilateral asymmetric chronic disease process characterised by progressive corneal thinning that results in irregular astigmatism and decreased visual acuity. The pathophysiology of keratoconus begins with a reduction in collagen lamellae within Bowman’s membrane (the second outermost of the five corneal layers, between the outer corneal epithelium and middle stromal layers). Progression of disease then affects the deepest corneal endothelial layer, distorting the morphology and tessellation of normal hexagonal shaped corneal endothelial cells (reduced pleomorphism), increasing the variation in cell size (polymegathism), but without affecting the overall number of corneal endothelial cells. In the UK, keratoconus has been shown to have a marked ethnicity split, with incidence in Caucasian British populations (3.3-4.5/100,000 population/year) significantly lower than in British Asian populations (19.6-25/100,000 population/year). Its onset and progression is usually in the second and third decades of life, with subsequent stabilisation thereafter, although progression may also occur in older affected individuals. Keratoconus management is usually conservative through monitoring and refractive correction, with complications such as corneal hydrops dealt with separately, and surgical treatment such as corneal collagen cross-linking, deep anterior lamellar keratoplasty (DALK), and penetrating keratoplasty (PK) usually reserved for those with more severe disease.